Input and output signals from a digital core of an integrated circuit (IC) may be provided externally to the integrated circuit through input/output cells, for example complementary metal oxide semiconductor (CMOS) IO Cells. In some systems, the power supply to the integrated circuit may differ to that of the external circuitry and the CMOS IO cell operates to convert a voltage from the digital core to a voltage in line with the power supply of the external circuitry.
ICs are often tested to check their functionality. As digital cores may be expected to operate under low supply voltage conditions, these conditions may be used to test the operation of the IC. In order for the output of the digital core under these test conditions to be analysed, the CMOS IO cells should also be able to handle the low voltage supply conditions.
Embodiments of the present application aim to address this.